Full-color Led Display True Color Display Technology Research

Based on the colorimetry theory, human visual characteristic and LED luminescence properties, this dissertation performs systemic study on the color correction method and control technique for true color display on full color LED video screen. Considering the difference of tricolor chromaticity coordinates between the LED video screen and the CRT screen, according to the color matching principle, a method for color correction based on the CIE colorimetric systems is presented and the conversion matrix is obtained, which improves the brightness and monochromatic purity greatly. According to the nonlinear intensity perception of human eyes, a method for color correction based on the human visual characteristics is obtained, it make the image coming from the television system more brilliant when printed on LED video screen. We investigate intensity-temperature characteristic of red, blue and green LED, test the variation of the intensity with the temperature, and propose a method for color correction based on the temperature characteristic of LED. It reduced the color distortion caused from the change of ambient temperature. In the process of LED electro-optic response, the nonlinear regularity of LED luminescence intensity as a function of PWM duty is studied, and a method for color correction based on the LED electro-optic response is acquired, on the basis of the simplified model of LED electric pulse response, the brightness control error caused from the process of LED response when using the PWM technology is effectively reduced. The technique of brightness control for LED video screen is studied, a control method of PWM based on binary-weight is put forward, the LED state is related to the binary bit of the image pixel value, it avoids the current shock and reduces the EMI. Considering that the refresh rate decreases rapidly when increasing the brightness level, a PWM control technique based on the global enable signal is put forward, such an improved PWM method makes use of the fact that the OE signal duration can be much shorter than the duration required for loading the entire sub-frame data, it improves the refresh rate and the gray-scale level of LED video screen. At last, the display module and control system of the full color video screen is designed, running results indicate that the color correction method and the control technique proposed in this paper are very useful, they greatly improves the color performance, working stability, brightness level and refresh rate of LED video screen.